Conventionally, digital image forming apparatuses having a function of transmitting image data to other devices have been known, for example, as disclosed in Japanese Unexamined Patent Publication No. 57868/1989 (Tokukaisho 64-57868). Such digital image forming apparatuses are known as a composite digital copying machine provided with not only a normal copy mode in which document image data as read by a scanner is printed by a recording section, but also a fax mode in which the image data is transmitted to other devices by means of a communication device and a communication line, etc.
The digital image forming apparatus disclosed in the described Gazette permits an automatic switching between the copy mode and the fax mode, and such arrangement permits an improved efficiency in copying or sending via facsimile the document image data, and also permits the image data as received in the fax mode to be output from the recording section.
The image data can be transmitted to a specific receiving end in the described fax mode of the digital image forming apparatus or by a generally used facsimile machine. However, in this case, the transmission of the image data is permitted only when the receiving end is fixed and can be identified. Namely, in the described method, emergency image data cannot be transmitted promptly if the receiving end cannot be identified, for example, when transmitting to a businessman who is always moving from one place to another to visit many clients.
On the other hand, when using the portable telephone that is widely used as a portable communication terminal, necessary information can be transmitted by communications even when the position of the person who possesses the portable telephone cannot be defined. However, such communication method does not permit image data to be transmitted.
In the opposite way of transmission where the businessman obtains a document to be transmitted to a predetermined receiving end immediately when he is at his destination, there is no way for him to transmit the document immediately unless he carries a portable facsimile machine. In practice; however, it is not convenient to carry such facsimile machine for its weight and size. Besides, when transmitting the document by the facsimile machine from his destination, it is troublesome to calculate a communication fee as it varies depending on distance, time, time range, service company, etc. Therefore, it is not easy to transmit the document by the described method.